<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>relative</title>
    <style>
        .fa{
            width:150px;
            height:150px;
            background-color: #cad53d;
            position: relative;
            left:30px;
            top:30px;
        }
        .fa div{
            width:50px;
            height:50px;
            background-color: blue;
            position: absolute;
            /*left:10px;*/
            /*top:10px;*/
        }
        .f2{
            width:150px;
            height:150px;
            background-color: pink;
            position: absolute;
        }
    </style>
</head>
<body>
<div class="fa">
    <div></div>
</div>
<div class="f2"></div>
</body>
</html>